Diaphragmatic dysfunction and alterations of thoracoabdominal motions are common in patients with chronic obstructive pulmonary disease (COPD). Several studies have described an impairment in diaphragmatic mobility of COPD patients compared to age matched control subjects and it has been associated with increase in dyspnea, exercise intolerance and mortality. COPD patients also experiment a higher activity of the accessory breathing muscles, which greatly increases the work of breathing and dyspnea sensation.